Mechanical ore-roasting furnace



MECHANICAL ORE ROASTING FURNACE Filed May 21, 1928 2 Sheets-Sheet 1 J. HARRIS MECHANICAL OREROASTING F URNACE Filed May 21, 1928 2 Sheets-Sheet 2 :Patented May 13, 1930 This invention relates to mechanical ore roasting furnaces'of the type "comprisingia series of super-imposed hearths through which a rabble shaft extends witharms oper- 5 ating over the varioushearths on which the ore is successively-rabbled in its passage tionbeing to reduce "orto avoid the forma- 7 tion of dust in the furnacebyproviding im- 10. provements in the method-and means of pass ing the ore from hearth tolhearth. 7 A fur-* ther object of the invention is to provideim-' proved'fiues for the draught andifor theipassage of gas through thejfurnace for alike -purpose.

Assuming an even draught through the furnace the chief cause of dust being formed in a furnace of the typer'eferried to appearsto be due to the fall of the :ore from hearth" to z hearth, the finer particles rising in dust as each batch of ore falls and being carried With the gasesthrOugh the furnace to create damage subsequentoperations; Toavoiddust from this cause it has been proposed to pass 3 the ore from an upper hearth to a lower one through a conduitr screening it from the draught through the" furnace, the conduit moving with the rabble shaft'and havingan 4 outlet opening at its;lowertrailingedge-ad- 1 jacent to the 'rabbling levelof the lower hearth; p c I i p; I a V V r Y Accordingto the present invention, however, the passage of ore from an upper hearth to a lower one is effected in stages of which 7 one is inte and through a fixed conduit depending from theupper hearth andanother is into and through a moving conduitbrought to register with the'fixed one by the rabblesliaft or arm. Preferably there is anintermedt' ate stage of the ore passage, the ore being temporarily retained in the fixed conduit which isclosed by a platform on therabble shaft or arm the moving conduit opening into, the platform and being subsequently brought to register with the fixed conduit; Thus not only is the ore screened fromthe; furnace draught by the conduits in its passage from hearth to heartlnbut each time it falls it is" from a smaller height than that betweenthe 99 hearths andh'ence the tendency to cause dust theplatforms, especially those of the heart-h receiving ore adjacent to therabble shaft, maybe comprised by an annulus or by sector ore adjacent to thef-path ofithepute yencl of Application filed ma a1, 1928; swam. 279,509, anafiiiqe at Britain J 'une 2, 19%

alsogrduced. rabble arm the lo'werhearthfmaypass below thefixed conduit after it" hasreceivedthe ore and before the moving conduit receives'it, especially when 1 the ore-isdeliVered at the outeredge ofl the circular path traversed by the rabbling arm. 1 through the furnace, the object of theinveni Ina; convenient: construction a fixed ore conduit'fopens through an upper heart h in arm or by thejshaft and is disposed to ex- H tend, the. fixedconduit to the rabbling level of thejlower hearth onceiin each revolution of ;'65

the, rabble shaft; Preferably the moving conduitj op'ensat itsu'pp'er end in aplatform carried by the lower rabble arm or; by the shaft, the platform extending in advance of the ,moving'conduit to close the. lower end j of the fixed one. The movingfc'onduit is prefer;

ably provided gwith anoutlet opening at its lower trailing edge s0,;that the, ore is; defposited therethrough as the conduit moves around-the shaft. 1 V V m Insin'gle shaft furnaces the'oreris, of course, delivered alternately adjacent to'the rabble shaft andadjacent to the path of the frcefend of thefrabble arm'on successive hearths, and f of an annulus concentric withthe shaft; I I V The platform of each hearthrecewmgthe therabble' arm is preferably carriedgat that end of the arm, extending in: advance thereof to close the'fixed conduit andain'rear there ,of tovcarrythe niovingconduit; the rabble arm of the upper hearthlbeing substantiallvlveu tically It "sthe usual practice in cylindrical Ifurnaces for'the ascending gases andfdraught through the furnaceftjo pass through the "openings in the various liearthsj down which theiore falls. Such;meetingoffascending gas with falling ore is janother pernicious cause of dust; and itistherefore'important to avoid a byprOVi ing flues for the ascending gases abovethe. armoftlie'lower hearth carfrying the platform.

path of the end rabble 17 which is nearest to the shaft 15 and operates over-the hearth12.

The conduit 21 depends to-apoint above the rabble arm 16 operating-overthe hearth 13 and a platform 22 is carried by this ar1n-16 or by theshaft 15 in such a position as to;be

capableofclosing the conduit 21. Inthe construction SlldWIl' in Figures 4, 5,-1.6 ands? the platform22 is in the form of .a.flanged annulus concentric with the shaft 15 and with .the lower end of the conduit 21 situated between its flanges. 1 2: 1 A moving conduit 23 is carried byQthe platform 22 and opensatits upper end in the platform. The moving conduit extendsdown to the rabbling levelf19. fof-thehearthl3,;the

arrangement and disposition of. the parts being such that the openingof the moving cone.

duit 23 in the-platform isbrought to "register with the fixed conduit 21' asj-ihe shaft rotates. Y V In operationjtheorerabbled bythearm 16 on the hearth 12will be moved towards the temporarily retained in the latterby. the; platform 22 will: fall into the moving conduit" which is provided withan outlet 24 opening at its lowertrailing edge as indicated. in'Figure 6 which illustrates thepositimi of the parts when the'ore passes from the fixecl conduit 21 into the moving one 23. During the further revolution of; the shaft 15 the ore'in the moving conduit. 23 will be graduallydeposited at the ra-bblinglevel of the hearth 13,

subsequently to come under-operation "of the rabbles 17 movingover that hearth. It will be understoodthat the operative 'oortion of theplatform 22 retainin ore in l i b .the fixed conduit 21 is the portionwhich ex tends in advance of theconduit 23 upto the fixed conduit at the. moment when. the. ore is delivered into the latter. The remainder of the annulus forming the platform 22 V be dispensed withif'desired, although itis preferred to retain it, first;to'seal the conduit 21 fronrthe furnace draught and secondly moving conduit to the shaft 15. i 31 Figures 8 :a'ndSilluStratefthe orepassage from the hearth 13 tothe hearth 14; at the outer'end of the arm 16*adjacentto thewall 10. In .this'cas'e the fixed conduit 21 extends abovethearch of the hearth 13 to the rabbling level19 thereon and theplatform 22 is'care I (ll ried at; the end of the arm16'operatingover temporarily blocked and 7 draught when a batch ofore fallsfrom one hearth to another. For this purpose; inlthe the. hearth. 14, .tl1e platform being suitably formed to engage the end of. the arm. The arm 16 operating. over the hearth'13 is preferablysubstantially vertically above the arm of. the lower hearth, the platform 22 extending sufiiciently in advance of-the arm carrying it'to closethe fixed conduit 21 when the rabbles of the upper hearth deliver a batch ofore intotheconduit; The platform '22'c'arries the moving conduit 23 on therearside of the arin; 16 so that gore deposited in the fixed-cond-uiti2lis temporarily retained theremars thence depositedat the mbbling level ofthehearthl h i The .ore1.;is' delivered into the, furnace through fi'xedconduits 21 operating in. combination with .a: movable conduit 23 as n scribed for. the passage-of the ore from hearth f to hearth- In'the construction illustratedthe fixed conduits 21: through-the hearth 11 are at the. periphery thereof and although two rabble} arms are shown operatingjover the hearth lluonliy the one .whicl1.-is.;,vertica1ly above thearmof the next, hearth 12 is opera tive to. feed'oreinto the conduits; the end rabbles of Itheother arm 'havingbeenomitted .to prevent ore-being delivered at at-ilnewhen 22 .is. not sealingthe-other end the platfor Ofthe conduit} in byitheplatform' 22until the arm of the hearth It has passed the. conduit 21; The orejthe'n.passesinto the moving conduit 23 In applying the invention to a rectangular furnace-the" draught through the {furnace passes'sfronrlhearth .1

applied to a" cylindrical furnace it is necessary gases separate from the ore passages from V, vhearththrough the i usual corner flues,but 'when the invention'is I hearth to hearthin order that-dust shallbe I causedneithertby the ascending gases meet; 4

ing the falling orenor bythe gas fluesbeing thereby choking the case: of. cylindrical furnace, the j draught through the furnace passes from hearth to hearth as vindicatedin'Fi'gures 2 and 3.The

'flues arepreferably made of metalland each comprisesacentral portion 25-.which is built The flue is alsoi provided-withian upper eninto thefcylindrical wall 10 of.:the" furnace. Theflue25is formed with a. lower enlarge ment 26'replacingpart of the-lowenhearth g 14 and providing aninlet below that hearth. to facilitate thefittingof the platform and i largement 27-. replacing partv of'the .upper hearth 13 and providing an outletbelow that hearthfthe. draughtthrough V the flue: from below. the hearth 14; and above it being indicated zbythe arrows in Figure 3;. -Thelower enlargement 26fdoes not extend. above the r'abblinglevel'19 ofythe hearth 14 nor does the upperenlargement-27 extend above the.

passage of ore from hearth to hearth, flues each comprising a central portion built in the furnace Wall between twohearthswitha lower 7 enlargement replacing part of the lower hearth and providing itsinlet and an upper enlargement replacing part of the upper hearth and providing its outlet, the flue or flues around the rabbling path of one hearth being substantially diametricall opposite 10 those around the rabbling path 0 the hearth above or below it. p a r I In testimony whereof I hereunto aflix my signature. JOHN HARRIS. 

